Dropdown list selection

Hi Friends I have one drop down list. in that drop down box i have to show only one value at a time.for Eg: I have one dropdown and one button. in my database i have 38 values. now i can populate those 38 values at a time to dropdown box. but my requirement is i have to show one by one to dropdown box. when i will click button 2nd value should be display in dropdown box, as well as 1st should be removed from dropdowm.